Salmonella-NLRP3 Inflammasome Crosstalk: Host Defense Activation Versus Bacterial Immune Evasion Strategies

Abstract

The innate immune system plays a crucial role in defending against Salmonella infection. Inflammasomes are macro-molecular complexes that assemble in response to the recognition of pathogen-or danger-associated molecular patterns. These complexes serve as signaling platforms for the activation of inflammatory Caspases, which subsequently triggers the maturation and secretion of the pro-inflammatory cytokines IL-1β and IL-18. This process also initiates pyroptosis, a highly inflammatory form of programmed cell death characterized by lytic cell lysis. Salmonella are intracellular pathogens that proliferate within epithelial cells and macrophages, posing a significant public health risk in both developed and developing countries. During Salmonella infection, the canonical NLRP3 and NLRC4 inflammasome, as well as non-canonical inflammasome, are activated. Unlike NLRC4 and non-canonical inflammasomes, which play crucial roles during intestinal infection phases, the role of NLRP3 inflammasome in resisting Salmonella infection demonstrates a higher degree of complexity and uncertainty. Nonetheless, the activation of NLRP3 inflamma-some, along with the downstream innate and adaptive responses, form a robust host immune barrier against potential pathogens. Therefore, successful pathogens must evolve multiple mechanisms to circumvent or counteract these immune barriers. Here we review and discuss the mechanisms of NLRP3 inflammasome activation triggered by intracellular Salmonella, as well as the multiple strategies employed by Salmonella to avoid or delay NLRP3 inflammasome activation. A deeper understanding of how NLRP3 inflammasomes recognize Salmonella and how pathogens evade NLRP3 activation has the potential to facilitate the development of novel prevention and control measures for Salmonella infection.